What do Ты think feeding on another vampire's blood means?

“Bloodsharing in vampire folklore — and certainly in the book mythology — is kind of sexual,” she explains. “It’s very intimate. It’s an exchange of bodily fluids, as they say, that Ты really shouldn’t be doing with anybody who’s not your one true vampire love. That’s the intention that we were going for there. In a weird way, Elena needing a fix was doing things that she shouldn’t have been doing to get help.” -Julie Plec

bloodsharing is a vampire mating activity it means that person really loves each other.